When Dana Hale adopted her son four years ago, she says she had to "play hardball" with her boss to get the same paid leave granted colleagues who give birth. The Washington employment lawyer knew then that if she and her self-employed husband adopted again, it would be under new management. So Hale began researching adoption-friendly workplaces, and soon focused on Capital One. The big financial-services company, headquartered in McLean, Va., offers $5,000 in assistance per adopted child, plus six weeks of paid leave. More important to Hale, the company fosters a supportive culture for adoptive parents, who network through a...